diff --git a/.changeset/little-bobcats-applaud.md b/.changeset/little-bobcats-applaud.md
new file mode 100644
index 00000000..781d7ab5
--- /dev/null
+++ b/.changeset/little-bobcats-applaud.md
@@ -0,0 +1,5 @@
+---
+"@content-collections/core": patch
+---
+
+Fixed watch on windows
diff --git a/packages/core/src/synchronizer.test.ts b/packages/core/src/synchronizer.test.ts
index 4ca2300d..57304f11 100644
--- a/packages/core/src/synchronizer.test.ts
+++ b/packages/core/src/synchronizer.test.ts
@@ -1,4 +1,4 @@
-import { describe, it, expect } from "vitest";
+import { describe, it, expect, vitest } from "vitest";
 import { createSynchronizer } from "./synchronizer";
 import { CollectionFile, FileCollection, ResolvedCollection } from "./types";
 
@@ -318,4 +318,79 @@ describe("synchronizer", () => {
 
     expect(collection.files.length).toBe(0);
   });
+
+  describe("posix", () => {
+
+    it("should add a new file", async () => {
+
+      vitest.mock("node:path", async (importOriginal) => {
+        const origin = await importOriginal<typeof import("node:path")>();
+        return {
+          default: {
+            ...origin,
+            sep: origin.posix.sep,
+            resolve: origin.posix.resolve,
+          },
+        };
+      });
+
+      const collection = {
+        directory: "content",
+        include: "**/*.md",
+        files: [],
+      };
+
+      const synchronizer = createSynchronizer(
+        createCollectionFileReader({
+          data: {
+            content: "changed",
+          },
+          path: "new.md",
+        }),
+        [collection]
+      );
+      expect(await synchronizer.changed("content/new.md")).toBe(true);
+
+      expect(collection.files.length).toBe(1);
+    });
+
+  });
+
+  describe("windows", () => {
+
+    it("should add a new file", async () => {
+
+      vitest.mock("node:path", async (importOriginal) => {
+        const origin = await importOriginal<typeof import("node:path")>();
+        return {
+          default: {
+            ...origin,
+            sep: origin.win32.sep,
+            resolve: origin.win32.resolve,
+          },
+        };
+      });
+
+      const collection = {
+        directory: "content",
+        include: "**/*.md",
+        files: [],
+      };
+
+      const synchronizer = createSynchronizer(
+        createCollectionFileReader({
+          data: {
+            content: "changed",
+          },
+          path: "new.md",
+        }),
+        [collection]
+      );
+      expect(await synchronizer.changed("content\\new.md")).toBe(true);
+
+      expect(collection.files.length).toBe(1);
+    });
+
+  });
+
 });
diff --git a/packages/core/src/synchronizer.ts b/packages/core/src/synchronizer.ts
index af240505..d40998da 100644
--- a/packages/core/src/synchronizer.ts
+++ b/packages/core/src/synchronizer.ts
@@ -27,8 +27,8 @@ export function createSynchronizer<T extends FileCollection>(
     const resolvedFilePath = path.resolve(filePath);
 
     let relativePath = resolvedFilePath.slice(resolvedCollectionPath.length);
-    if (relativePath.startsWith("/")) {
-      relativePath = relativePath.slice(1);
+    if (relativePath.startsWith(path.sep)) {
+      relativePath = relativePath.slice(path.sep.length);
     }
     return relativePath;
   }